Accelerated break circuit interrupter



Nov. 29, 1.938. J. D, HlLLlARD 2,138,323

ACCELERTED BREAK CIRCUIT INTERRUPTER Filed Deo. 9, 1933 Patented Nov.29, 1938 PATENT OFFICE AccELERA'rEn BREAK CIRCUIT` INTER- RUPTER John D.Hilliard,

Glens Falls, N. Y.

Application December 9, 1933, Serial No. '701,611

8 Claims.

This invention relates in general to circuit breakers and moreparticularly to circuit breakers of the pressure pot type having meansfor accelerating the interruption of the current by utilizing thepressure generated within the pressure pot to increase the contactseparating speed and by providing the pressure pot with a plurality ofsmall discharge throats.

yThe major factor which determines the interrupting capacity of acircuit breaker is the amount of gas generated during circuitinterruption. In general, the amount of gas generated is proportional tothe kv-a interrupted and the arcing time. The arcing time may be reducedby increasing the speed of separation of the contacts.

It is known that the pressure generated by an arc within the pressurepot of a circuit breaker will act upon the movable contact rod and thisprinciple has been utilized in British Patent No. 147,456, April 28,1921, however. if the movable contact rod is xedly secured to thecontact operating arm, to avoid the use of pigtail conductors, themovable contact must be of large diameter in order to obtain anappreciable increase in Contact speed. An increase in the diameter ofthe Contact rod necessarily increases the size of the throat openingthrough which the contact rod passes. It is known that pressure potshaving large throat openings are less efficient in extinguishing an arcthan pressure pots having smaller throat openings.

It is therefore an object of the present invention to improve theoperation of a circuit breaker of the pressure pot type by providing oneor more auxiliary plungers which extend into the pressure pot and areacted upon by the pressure generated Within the pressure pot to increasethe separating speed of the movable contacts.

Another object of the invention is to provide a circuit breaker of thepressure pot type with one or more auxiliary contact acceleratingplungers in order that the discharge opening or openings through whichthe arc is drawn may be of efficient size.

A further object of the invention is to provide a circuit breaker of thepressure pot type with a plurality of small movable Contact rodscooperating with small discharge openings so that the arc which is drawnby certain of these contacts I may be readily extinguished in thedischarge openings and the other contact rods may be utilized toaccelerate the interrupting movement of the circuit breaker.

A still further object of the invention is to pro- (Cl. ZOU-150) vide acircuit breaker of the pressure pot type with a plurality of parallelconnected movable contacts withdrawable through a plurality of dischargeorifices to break contact with a plurality of parallel connectedstationary contacts within the pressure pot.

These and other objects and advantages are attained by this invention,various novel features of which will be apparent from the descriptionand drawing herein, and will be more particularly pointed out in theclaims.

Various illustrative examples of the application of this invention areshown in the accompanying drawing in which:

Fig. 1 is a vertical section view of a circuit breaker having mechanismassociated with the pressure pot thereof embodying the presentinvention;

Fig. 2 is a vertical section view of a modified form of a circuitbreaker pressure pot mechanism embodying the present invention;

Fig. 3 is a vertical section vieW of another form of circuit breakerembodying the present invention; and

Fig. 4 is a horizontal section View of Fig. 3 taken along the lineIV-IV.

Referring now to Fig. l, 5 is a circuit breaker tank which contains abody of arc extinguishing liquid E. An insulating bushing l is supportedfrom the housing (not shown) of a circuit breaker and has a conductorrod 8 extending therethrough. The upper wall 9 of a pressure pot IO issecured to bushing 'l by any suitable known means such as conductor 8. Astationary contact II, here shown as of the tulip type, is secured towall member 9. Bleeder openings I3 are provided in the wall member 9. Ashell member I4 is suitably secured to wall member 9 and is providedwith an aperture in the bottom thereof through which throat bushing I5of insulating material projects. An insulating tube 29 within shellmember I4 serves to insulate the interior of the pressure pot.Insulating shell member I6 surrounds shell I4 and is held in place bysuitable means such as insulating nut mem ber Il. A movable contact rodI8 normally extends through the throat opening of bushing I5 intoengagement with stationary contact II and is xedly secured to contactactuating member I9 which is operated by any suitable known mechanismwhich is not shown for the sake of simplicity.

An auxiliary plunger member 2U, preferably of insulating material,extends through an opening 2I in the pressure pot ID and is preferablyprovided at one end with a cap member 22, noting that the other endthereof abuts against contact actuating member I9.

Upon circuit interrupting movement of contact actuating member I9, anarc will be drawn between movable contact I8 and stationary contact I Iwithin pressure pot IU which is normally iilled with arc extinguishingliquid. The heat of said arc will dissociate a portion of this liquidand thereby generate pressure which will operate on the plunger member2U to increase the downward speed thereof. Inasmuch as the combinedcrosssectional area of contact I8 and plunger 20 is subjected to thepressure within pressure pot I0, contact I8 will be moved downwardly athigh speed thus minimizing the amount of gas generated within pressurepot I and thus enabling the orice in throat bushing I to be madesufiiciently small that a highly effective blast of arc extinguishingliquid is projected in the path of the arc upon the movement of contactI8 through the throat bushing. It is to be understood that plunger 2!may be secured to contact actuating member I9 in the manner shown inFig. 2 if desired, and hole 2| may have an insulating bushing.

Fig. 2 is substantially the same as Fig. 1 except that the auxiliaryplunger 2D is secured to contact actuating member I9 by means of member25 and is slidable in a tube 23 of insulating material which is incommunication with the interior of pressure pot i0 by way of nipplemember 24 which with member 23 forms an auxiliary passageway 2I. In Fig.2 a bracket member 2B is interposed between thread nut member II andshield member I6 in order to hold tube member 23 rmly in position.

The operation of Fig. 2 is substantially the same as that described inconnection with Fig. 1 except that, as shown in Fig. 2, auxiliaryplungermember 20 may be completely withdrawable from tube member 23. Uponwithdrawal of plunger rod 2D from tube member 23, the acceleratingaction thereof will cease, however, it is to be understood that thelength of plunger rod 20 may be shorter or longer than as shown in Fig.2 in order that the duration of this action may be controlled.

In Fig. 3 a plurality of stationary contacts II are secured to the upperplate member 9 which serves to connect these contacts in parallel. Ashere shown, contacts II are of the tulip type, however, other knowntypes of contacts may be used, such as spring biased butt contacts. Athroat bushing member 21 is secured to shell member I4 by means of nutmember I`I which also serves to hold insulating shield I 6 in place. Abottom plate member 28 of insulation with a plurality of dischargeorices therein is here shown as resting on member 21 and is held inplace by inner shield member 29 which is biased downwardly by theclamping action of bolts 30. A plurality of movable contacts I8 aresecured to contact actuating member I9 and are thus connected inparallel. Although ve movable contacts have been shown, it is to beunderstood that the number of contacts may be increased or decreased,noting that a symmetrical arrangement should be maintained in order thatthe forces acting on the movable contacts due to the pressure withinpressure pot IS will not cause actuating member I9 to tilt or move outof alinement.

Contact actuating member I9 is operated by any suitable known operatingmechanism (not shown) which usually comprises a spring capable of movingcontacts I8 to their lowermost position in a predetermined time. B yreason of the fact that the combined cross-sectional area of contactrods I8 is preferably greater than the crosssectional area of a singlecontact would be in a conventional pressure pot breaker, the pressureaction on contacts I8 will considerably augment the downward speed ofthese contacts thus reducing the arcing time of the breaker. A singlecontact rod having the same cross-sectional area as the totalcross-sectional area of contact rods I8 would require a throat dischargeopening so large that efiicient throat action could not be secured, thatis, the velocity and turbulence of the discharge of arc extinguishingfluid through the throat would not be sufficient to rapidly extinguishthe arc.

Upon downward movement of contacts I8 one or more arcs will be drawnthrough the discharge orifices in plate member 28 and inasmuch as theseorifices are only slightly larger than the relatively small contact rodsI8 a highly eiiicient blast action is obtained as well as an increaseinthe downward speed of the contacts I8 due to the pressure actionthereon. In service the renewable tips on contact rods I8 will begradually burned away, however, the longest contact rods, that is, thelast ones to break contact, will take the greatest amount of burning sothat the contact rods will automatically maintain substantially the samelength. It is thus apparent that a circuit breaker such as abovedescribed will require less inspection and less renewal of contacts.

The use of the present invention permits the throat oriiice area to bedesigned entirely on the basis oi efficiency of throat action, and notdependent upon the movable contact size which will give proper openingspeed due to the piston action. Such design permits the throat to bemade sufficiently small so that the arc therein is con,- ned in a regionof great turbulence, cooling and deionization, whereas if the throat isdesigned large enough to permit movement therethrough of a movingcontact large enough to provide the desired contact separating speed dueto the piston action, it does not provide the necessary confinement oithe arc so that the throat action due to turbulence, cooling anddeionization is sufficiently eicient. With the throat size that whichprovides the most efcient throat action, the increased speed is obtainedby the added piston members which are operatively independent of thethroat size.

Although only a few embodiments of the present invention have beenillustrated and described, it is to be understood that modifications andchanges therein may be made by those skilled in the art withoutdeparting from the spirit of the invention or from the scope of thefollowing claims.

It is claimed and desired to secure by Letters Patent:

l. In a circuit breaker, the combination of a pressure pot having acontact passageway and a second passageway therein, a stationary contactmounted within said pressure pot, a movable contact substantiallyclosing said contact passageway and extending therethrough forengagement with said stationary contact, a movable contact carryingmember operable to disengage said movable contact from said stationarycontact to draw a pressure generating arc within said pot, and meansutilizing said pressure for accelerating the disengaging movement ofsaid movable contact comprising an auxiliary member operable in saidsecond passageway independently of the cross sectional area of saidcontact passageway.

2. In a circuit breaker, the combination of a pressure pot having adischarge passageway therein, the cross sectional area of said passage-Way being sufficiently small tor provide efficient throat action of saidcircuit breaker during interruption, a iixed contact mounted within saidpressure pot, a movable contact member Withdrawable through saiddischarge passageway to break contact with said fixed contact andthereby draw a pressure generating arc in said pressure pot, and meansfor accelerating the speed of said moving contact comprising pistonmeans within said pressure pot.

3. In a circuit breaker, the combination of a pressure pot immersed inan arc extinguishing liquid and having a discharge orifice of a sizeproviding substantial throat efhciency, a fixed contact mounted Withinsaid pressure pot, a contact actuating member, a movable contact securedto said actuating member and withdrawable through said orifice to draw apressure generating arc within said pressure pot, said pressure pothaving another orifice therethrough, a piston device slidable throughsaid another orifice into engagement with said contact actuating memberand operable to increase the Contact separating speed of said contactactuating member in response to the pressure generated Within saidpressure pot.

4. In a circuit breaker, the combination of a pressure pot immersed inan arc extinguishing liquid and having a discharge orifice, a xedcontact mounted Within said pressure pot, a contact actuating member, amovable contact secured to said actuating member and withdrawablethrough said pressure pot and said orifice and cooperable With saidfixed contact to draw a pressure generating arc Within said pressurepot, said pressure pct having another discharge orifice therethrough,another movable contact provided with a closed end and slidable throughsaid another orifice and secured to said contact actuating member, saidanother Contact member being operable to increase the contact separatingspeed of said contact actuating member in response to the pressuregenerated Within said pressurepot.

5. In a circuit breaker, the combination of a pressure pot having aplurality of discharge passagevvays therein, a plurality of stationarycontacts mounted Within said pressure pot in alinement with saidpassageways, a plurality of movable contacts normally closing saidpassageways and extending therethrough into engagement with saidstationary contacts respectively, a contact actuating member operable toWithdraw said movable contacts from said pressure pot through saiddischarge passageways to cause at least one pressure generating arcWithin said pressure pot, said movable contacts also serving as pistonsto increase the contact separating speed of said Contact actuatingmember in response to the pressure generated Within said pressure pot.

6. In a circuit breaker, the combination of a pressure pot having aplurality of discharge passageways therein, a plurality of stationarycontacts multiply connected and mounted Within said pressure pot inalinement with said passage- Ways, a plurality of movable contactsnormally closing said passageways and extending therethrough intoengagement with said stationary contacts respectively, a contactactuating member connecting said movable contacts in multiple andoperable to simultaneously withdraw said movable contacts through saiddischarge passageways to draw at least one arc Within said pressure potand through at least one of said discharge passagevvays.

7. In a circuit breaker, the combination of a pressure pot immersed inan arc extinguishing liquid, said pressure pot having one wall ofinsulating material with a plurality of holes therein and an oppositeWall of conductive material, a plurality of stationary contacts mountedon said conductive wall in alinement with said holes respectively, acontact actuating member, a plurality of movable contacts provided withsubstantially closed ends and mounted on said actuating member andarranged for simultaneous Withdrawal through said holes to draw aplurality of arcs in parallel through said holes, Whereby the arcextinguishing liquid Within said pressure pot is caused to blast in thepath of said arcs.

8. An oil circuit breaker of the type comprising a pressure chamber, astationary contact mounted in said chamber, a discharge orifice in saidchamber in alinement with said stationary contact, a contact movablethrough said orifice and cooperating with said stationary contact todraw a pressure generating arc, and means for accelerating the operatingspeed of said movable: contact, said means. comprising additionaldischarge orifices of an area less than the area of said iirst saiddischarge orifice., said means further comprising additional movingcontact members operating through said additional discharge orifices.

JOHN D. HILLIARD.

